It's 2084, and the Cold War is still on. We're deep down on the Ocean
floor in a military seabase that's armed with missiles and everything.
Thing is, these missiles can only be fired telepathically, using
brainwaves only apparent in certain people ... and wouldn't you know it,
the guy originally intended to fire the rockets in an emergency has just
died under mysterious circumstances, leaving the job to mentally unstable
Maddox (Martin Neil) ... of course all of this is sabotage, and the
culprits are foreign agents Nilson (Ian McCulloch) and Doc Solow (Ingrid
Pitt), who work at the base undercover (obviously) and who get their hands
on Maddox' brainwaves, which they save on a computer disk and then
mindcontrol him

Amidst all that chaos, Doctor Who (Peter Davison) and his companions
Tegan (Janet Fielding) and Turlough (Mark Strickson) land on the base in
their time-and-space machine TARDIS ... and are immediately suspected to
be foreign agents and apprehended.

As if all that wasn't enough, the Silurians have just woken up from
hibernation and now decide to enlist the help of the Sea Devils and a
dragon called Myrka to take over the seabase and cause a nuclear war
between the two blocs that will completely wipe out the human race and
allow the Silurians to repossess the planet that was once theirs - and
suddenly the base's commander Vorshak (Tom Adams) and everyone aboard have
to realize the Doctor is the only one who can help them - even if Nilson
and Solow still try to get away with Maddox brainwaves stored on a disk,
obviously oblivious to the greater danger of the Silurians and the Sea
Devils. Of course, both of them get their just desserts in the end.

Feverishly, the Doctor tries to negotiate a peace treaty between all
parties involved, but ultimately the Silurians manage to start the
countdown to launch the base's missiles even without Maddox' brainwaves
which would effectively start World War III - but somehow the Doctor can
stop the countdown in the nick of time using his own, superior brainwaves.
However, in a final shoot-out between humans on one side, and Silurians
and Sea Devils on the other (the dragon has been killed earlier on)
everybody but the Doctor and his companions has let his/her life.

The start of this story isn't too bad, reminiscent of the best Tom
Baker episodes from roughly ten years earlier, but then the episode falls
apart: The combination of the (way too blunt) Cold War subplot and the
Silurians plot just doesn't make sense and slows the story down, too much
time is taken up by the story's setup that ultimately leads to nowhere,
and the dragon that has been thrown into the story makes little sense and
is a horrible costume. Add to this the Silurians and the Sea Devils, both
monsters from the wackier end of the series (costume-wise), totally
overlit sets and a reportedly rushed production schedule (rushed even by
the series rushed standards) and you've got one pretty bad episode - of
which there were many when John Nathan Turner was the series' producer.